Effect of Local Loads on the Stability of Shells Subjected to Uniform Pressure Distribution

1992 ◽  
pp. 42-51
Author(s):  
Lars Å. Samuelson
Keyword(s):  
Pressure Distribution ◽  
Uniform Pressure ◽  
Local Loads ◽  
The Stability

Development of a laminar boundary layer under conditions of continuous incipient separation

1976 ◽  
Vol 76 (1) ◽  
pp. 55-66 ◽  
Author(s):  
N. Curle
Keyword(s):  
Boundary Layer ◽  
Pressure Distribution ◽  
Laminar Boundary Layer ◽  
Shape Parameter ◽  
Uniform Pressure ◽  
Continuous Change ◽  
Similar Series ◽  
Image Position ◽  
Incipient Separation

SynopsisThis paper, extending the work of Stratford [6] considers a boundary layer with uniform pressure when x < x0, and with the pressure in x > x0 so chosen that the layer is just on the point of separation for all x >x0. The required pressure distribution is shown to beThe displacement and momentum thicknesses are also derived as series in powers of ξ (and log ξ), and the shape parameter H then obtained as a similar series. The continuous change in H from the Blasius value (when ξ = 0) towards the Falkner-Skan [3] separation value is convincingly demonstrated, with the aid of the leading terms of an asymptomatic expansion for large ξ.

Physics of the Slipping Wheel. I. Force and Torque Calculations for Various Pressure Distributions

1969 ◽  
Vol 42 (4) ◽  
pp. 1014-1027 ◽  
Author(s):  
D. I. Livingston ◽  
J. E. Brown
Keyword(s):  
Pressure Distribution ◽  
Lateral Force ◽  
Slip Angle ◽  
Uniform Pressure ◽  
Elliptical Distribution ◽  
Side Force ◽  
Contact Patch ◽  
Pressure Distributions ◽  
Parabolic Distribution

Abstract Slipping wheel theory has been extended to predict the dependence of the lateral force and of the aligning torque on the nature of the pressure distribution over the contact patch between the wheel and the ground. Expressions have been derived for both side force and aligning torque as functions of the slip angle under: uniform pressure distribution, which applies to the behavior of an inflated membrane wheel; elliptical distribution, which describes the behavior of a solid wheel; and parabolic distribution. All appear appropriate in some respect to the actual tire.

Modelling and Analysis of the Dynamic Behavior of an Active Journal Bearing

1994 ◽  
Author(s):  
Linxiang Sun ◽  
Janusz M. Krodkiewski ◽  
Nong Zhang
Keyword(s):  
Pressure Distribution ◽  
Reynolds Equation ◽  
Hydrodynamic Pressure ◽  
Chamber Pressure ◽  
Oil Film ◽  
Simulation Based ◽  
Rotor Bearing ◽  
New Type ◽  
The Stability ◽  
Bearing System

Modelling and analysis of a rotor-bearing system with a new type of active oil bearing are presented. The active bearing basically consists of a flexible sleeve and a pressure chamber. The deformation of the sleeve can be controlled by the chamber pressure during the operation, and so can the pressure distribution of the oil film. Finite Element Methods (FEMs) and the Guyan condensation technique were utilised to create mathematical models for both the rotor and the flexible sleeve. The hydrodynamic pressure distribution of the oil film, for the instantaneous positions and velocities of the flexible sleeve and rotor, was approximated by Reynolds equation. The influence of the chamber pressure on the stability of the rotor system was investigated by numerical simulation based on the nonlinear model. The results showed that the stability of the rotor-bearing system can be improved effectively by implementation of the active bearing.

Stability of Gas Injection Using Lateral Wells in Layered Oil Reservoirs

2007 ◽  
Vol 18-19 ◽  
pp. 271-276
Author(s):  
E. Steve Adewole ◽  
B.M. Rai
Keyword(s):  
Pressure Distribution ◽  
Gas Injection ◽  
Oil Production ◽  
Bottom Layer ◽  
Oil Reservoirs ◽  
Mobility Ratio ◽  
Fluid Velocities ◽  
The Stability ◽  
Gas Cycling ◽  
Gas Properties

The stability of gas injection in a layered reservoir drilled with lateral wells, is studied using a generalized pressure distribution-dependent mobility ratio expression. Stable injection guarantees clean oil production. The mobility ratio compared layers’ fluid velocities across a common permeable interface. Studies were based on injected gas compressibilities and viscosities only. Results show that injection stability is affected by (1) injected gas properties, and (2) injection layer; i.e., whether gas cycling (bottom layer injection) or gas injection (top layer injection). Gas cycling tends to exhibit more instability than gas injection operation.

scholarly journals Analysis of the Elastic Large Deflection Behavior for Metal Plates under Nonuniformly Distributed Lateral Pressure with In-Plane Loads

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Jeom Kee Paik ◽  
Ju Hye Park ◽  
Bong Ju Kim
Keyword(s):  
Pressure Distribution ◽  
Large Deflection ◽  
Lateral Pressure ◽  
Water Pressure ◽  
Offshore Structures ◽  
Design Methods ◽  
Uniform Pressure ◽  
Bending Moments ◽  
Maritime Industry ◽  
Metal Plates

The Galerkin method is applied to analyze the elastic large deflection behavior of metal plates subject to a combination of in-plane loads such as biaxial loads, edge shear and biaxial inplane bending moments, and uniformly or nonuniformly distributed lateral pressure loads. The motive of the present study was initiated by the fact that metal plates of ships and ship-shaped offshore structures at sea are often subjected to non-uniformly distributed lateral pressure loads arising from cargo or water pressure, together with inplane axial loads or inplane bending moments, but the current practice of the maritime industry usually applies some simplified design methods assuming that the non-uniform pressure distribution in the plates can be replaced by an equivalence of uniform pressure distribution. Applied examples are presented, demonstrating that the current plate design methods of the maritime industry may be inappropriate when the non-uniformity of lateral pressure loads becomes more significant.

Pressure Distribution for Patchlike Contact in Seals With Frictional Heating, Thermal Expansion, and Wear

1976 ◽  
Vol 98 (4) ◽  
pp. 596-601 ◽  
Author(s):  
S. R. Kilaparti ◽  
R. A. Burton
Keyword(s):  
Thermal Expansion ◽  
Pressure Distribution ◽  
Influence Function ◽  
Frictional Heating ◽  
Leading Edge ◽  
Simultaneous Equations ◽  
Sliding Contact ◽  
Maximum Pressure ◽  
Uniform Pressure ◽  
Deformed State

Sliding contact in seals is known to change at high sliding speed from initially uniform pressure to a deformed state where contact is restricted to small patches of the surface. An earlier analysis of such contact was based upon the assumption of uniform pressure on the small patches. The present study draws upon a thermoelastic influence function to provide simultaneous equations for pressure on subdivisions of the patches. The final result is that at high wear rate (and, consequently, high traversal speed of the patch along the surface of the more conductive body of the contacting pair) the pressure distribution becomes roughly triangular with the maximum pressure toward the leading edge of the patch.

scholarly journals Using Finite Element Methods to Calculate the Deflection of an Orifice Plate Subject to Uniform Pressure Distribution

2016 ◽  
Author(s):  
Aneet Dharmavaram Narendranath ◽  
Prathamesh Deshpande ◽  
Madhu Kolati ◽  
Datta Sandesh Manjunath
Keyword(s):  
Finite Element ◽  
Pressure Distribution ◽  
Finite Element Methods ◽  
Orifice Plate ◽  
Uniform Pressure

A General Solution for Optimized Circular Contacts

2004 ◽  
Author(s):  
Marilena Glovnea ◽  
Emanuel Diaconescu
Keyword(s):  
General Solution ◽  
Pressure Distribution ◽  
Edge Effects ◽  
Contact Area ◽  
Front Surface ◽  
Electrical Contacts ◽  
Machine Design ◽  
Central Pressure ◽  
Uniform Pressure ◽  
Optimum Pressure

Many classical applications in machine design and recent ones in the field of electrical contacts or micro-contacts involve surface circular contacts which show important edge effects. To optimize these contacts, a uniform pressure distribution must be generated over an important part of contact area. This requires a specifically profiled front surface. Previously, these authors proposed a solution based on an optimum pressure distribution. This leads numerically to a punch profile which is approximated by a polynomial. The pressure generating this polynomial profile is found and compared to initial proposal. Recent investigations establish a correspondence between a polynomial punch surface and generated pressure. Starting from this correspondence, a new general approach is offered. The same optimum pressure as previously is accepted. Its profile is approximated by a function advanced in the paper. This function yields directly an even polynomial punch profile. Formulae for central pressure and normal approach are derived.

scholarly journals Experimental determination of optimal clamping torque for AB-PEM Fuel cell

2016 ◽  
Vol 6 (1) ◽  
pp. 9 ◽  
Author(s):  
Noor Ul Hassan ◽  
Murat Kilic ◽  
Emin Okumus ◽  
Bahadir Tunaboylu ◽  
Ali Murat Soydan
Keyword(s):  
Fuel Cell ◽  
Contact Resistance ◽  
Pressure Distribution ◽  
Gas Permeability ◽  
Compaction Pressure ◽  
Pem Fuel Cell ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Uniform Pressure ◽  
Torque Values

<span lang="EN-GB">Polymer electrolyte Membrane (PEM) fuel cell is an electrochemical device producing electricity by the reaction of hydrogen and oxygen without combustion. PEM fuel cell stack is provided with an appropriate clamping torque to prevent leakage of reactant gases and to minimize the contact resistance between gas diffusion media (GDL) and bipolar plates. GDL porous structure and gas permeability is directly affected by the compaction pressure which, consequently, drastically change the fuel cell performance. Various efforts were made to determine the optimal compaction pressure and pressure distributions through simulations and experimentation. Lower compaction pressure results in increase of contact resistance and also chances of leakage. On the other hand, higher compaction pressure decreases the contact resistance but also narrows down the diffusion path for mass transfer from gas channels to the catalyst layers, consequently, lowering cell performance. The optimal cell performance is related to the gasket thickness and compression pressure on GDL. Every stack has a unique assembly pressure due to differences in fuel cell components material and stack design. Therefore, there is still need to determine the optimal torque value for getting the optimal cell performance. This study has been carried out in continuation of deve­lopment of Air breathing PEM fuel cell for small Unmanned Aerial Vehicle (UAV) application. Compaction pressure at minimum contact resistance was determined and clamping torque value was calcu­la­ted accordingly. Single cell performance tests were performed at five different clamping torque values i.e 0.5, 1.0, 1.5, 2.0 and 2.5 N m, for achieving optimal cell per­formance. Clamping pressure distribution tests were also performed at these torque values to verify uniform pressure distribution at optimal torque value. Experimental and theoretical results were compared for making inferences about optimal cell perfor­man­ce. A clamp­ing torque value of 1.5 N m was determined experimentally to be the best for getting optimal performance as well as uniform pressure distribution for this specific fuel cell.</span>

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